Measuring the concentration of substances, particularly in the presence of other substances, is important in many fields, and especially in medical diagnostics. For example, the measurement of glucose in body fluids, such as blood, is crucial to the effective treatment of diabetes.
Proper regulation of blood glucose fluctuations requires accurate measurement of the concentration of glucose in the blood. Failure to do so can produce extreme complications such as blindness and loss of circulation in the extremities.
Multiple methods are known for measuring the concentration of glucose in a blood sample. Such methods typically fall into one of two categories: optical methods and electrochemical methods. Optical methods generally involve the use of reflectance or absorbance spectroscopy to determine the glucose concentration. In optical methods, a chemical reaction produces a color change indicative of the concentration of glucose. Electrochemical methods generally involve measuring amperometric or coulometric responses that are proportional to the concentration of glucose.
Multiple contributing factors, such as variations in blood composition, limit the accuracy of blood glucose measurements. For example, variations in hematocrit, the concentration of red blood cells, can affect the signal generated by the interaction of a blood sample with the test reagent. Variations in the temperature at which the glucose is measured may also affect the accuracy of the blood glucose result.